Inventory planning tool

Inventory Reorder Calculator

Calculate reorder point, safety stock, and suggested reorder quantity so you can reduce stockouts without overbuying.

Built for makers, handmade sellers, and small product businesses.

Planning estimate

This calculator provides planning estimates based on the inputs you enter. Actual reorder decisions should also consider seasonality, supplier reliability, minimum order quantities, cash flow, and product shelf life.

For volatile products, review reorder settings regularly and update demand and lead time assumptions as conditions change.

Calculator

Plan when to reorder before stock gets tight

Calculation mode

Use 1 if you can reorder in single units. Use 6, 12, or another pack size if your supplier requires it.

Adds extra cover on top of the reorder point and lead time demand when suggesting a reorder quantity.

Results

Inventory planning at a glance

Reorder status

Reorder now

Reorder point

126

Safety stock

84

Lead time demand

42

Inventory position

40

Days of cover

13.3

Suggested reorder quantity

149

Reorder recommendation

You should reorder now because your inventory position is 86 units below the reorder point.

Suggested reorder quantity is 149 units based on the reorder point, one lead time of demand, and the current reorder target.

Breakdown

Inputs and buffers behind the reorder trigger

Average daily demand

3

Average lead time

14 days

Lead time demand

42

Safety stock

84

Reorder point

126

Inventory position

40

Buffer below reorder point

86

How this is calculated

How your current inventory reorder numbers are calculated

This walkthrough updates live from the form so you can see how lead time demand, safety stock, reorder point, and the suggested reorder quantity are built.

Open the live calculation walkthroughUses your current inventory planning inputs and results.
Input
Current simple-mode inputs: average daily demand = 3, maximum daily demand = 6, average lead time = 14 days, maximum lead time = 21 days, current stock on hand = 40, units already on order = 0, pack size = 1, extra days after reorder = 7.
Formula
Lead time demand = average daily demand x average lead time days = 3 x 14 = 42.
Formula
Simple safety stock = (max daily demand x max lead time days) - (average daily demand x average lead time days) = (6 x 21) - (3 x 14) = 84.
Result
Reorder point = lead time demand + safety stock = 42 + 84 = 126.
Result
Inventory position = current stock on hand + units already on order = 40 + 0 = 40.
Result
Suggested reorder quantity = max(0, reorder point + lead time demand + average daily demand x extra days after reorder - inventory position) = max(0, 126 + 42 + 3 x 7 - 40) = 149.
Meaning
In plain English: the reorder point tells you when your inventory position is low enough that it is time to place the next order, while the suggested reorder quantity aims to get you through the next lead time with an extra planning buffer.

How it works

What this inventory calculator is actually helping you decide

The goal is not only to find a number. It is to understand when to reorder, how much uncertainty to buffer, and how aggressive your stock policy should be.

What reorder point means

Reorder point is the inventory trigger. It tells you when the stock position is low enough that you should place the next order before normal demand and supplier lead time eat through the remaining units.

What safety stock means

Safety stock is your demand and lead-time buffer. It exists to absorb uncertainty when actual sales run higher than expected or a supplier takes longer than planned.

Why lead time matters

Lead time demand is the inventory you expect to sell before the next order arrives. Underestimating lead time is one of the fastest ways to create stockouts even when the reorder point looks reasonable on paper.

When EOQ is useful

EOQ is most useful when you track annual demand, ordering cost, and carrying cost. It does not replace reorder point, but it can help decide whether each order should be bigger or smaller.

FAQ

Common questions

Short answers to the inventory planning questions makers and small product businesses ask most often.

What is a reorder point?

A reorder point is the inventory level where you should place the next purchase order so stock can arrive before you run out under your current demand and lead time assumptions.

What is safety stock?

Safety stock is extra buffer inventory held above expected lead time demand to reduce the risk of stockouts when demand spikes or supplier lead times slip.

How often should I update reorder points?

Review reorder points regularly whenever demand patterns, seasonality, supplier reliability, lead times, or product mix change. Volatile products usually need more frequent updates.

What service level should a small business use?

Many small product businesses start around 95% and then adjust based on stockout cost, cash flow, and supplier reliability. Higher service levels increase safety stock and reduce stockout risk, but they also tie up more cash in inventory.

What is EOQ and do I need it?

EOQ, or economic order quantity, estimates an order size that balances ordering cost against holding cost. It is useful when you track both costs, but it is optional and not required to calculate reorder point or safety stock.

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